Process oils are used in silicon rubber compositions as a cheap extender oils to reduce formulation costs. Key requirements for process oils for this application are full silicon oil compatibility but also good UV stability and low volatility. Widely available extender oils used for this purpose are naphthenic oils and hydroprocessed paraffinic petroleum oils. Hydroprocessed paraffinic petroleum oils are preferred for this use.
A disadvantage of the use of hydroprocessed paraffinic petroleum oils is that although some oils show excellent UV stability they show reduced silicon oil compatibility at higher oil contents.
It would be useful to provide a silicon rubber composition wherein the content of extender oil can be increased while properties such as UV stability and volatility are not worsened as compared to when a hydroprocessed paraffinic petroleum derived oil is used because of their low volatility and good UV stability.
The invention is directed to a silicon rubber composition comprising a hydrocarbon extender oil, wherein the oil is a Fischer-Tropsch derived oil.
The invention is also directed to a process for making an extender oil.